Preface. Dahlia, also known as dahlias, dahlias, geranium peonies or passionflowers, belongs to the genus Dahlia of the Asteraceae family, and is a perennial root flower.
It is also known as "sweet potato flower" because of its hypertrophied spindle-shaped fleshy tubers in its underground part, which resemble sweet potatoes in shape.
The stem of the dahlia is hollow, usually between 30 and 100 cm in height, and the leaves are opposite, with 1 to 3 pinnate shapes**.
The leaflets are ovate or elliptic, dark green on the front and gray-green on the back, with coarse blunt serrations on the margins, and the total stalk slightly winged. The inflorescence is capitate, with a long peduncle, and can be apical or axillary.
Dahlias vary in size, color, and shape depending on the variety, and the inflorescence consists of tongue-like flowers on the periphery and tubular flowers in the middle, which can be unisexual or neutral, while tubular flowers are bisexual.
The tongue-shaped flowers on the periphery are rich and showy, and in addition to blue, there are various colors such as purple, red, yellow, snow blue, pink, sprinkled gold, white, and golden yellow, and the tubular flowers in the center are yellow.
The flowering period is between June and October, and the fruit is a black achene, oblong or obovate, flattened.
Dahlia is known for its large, bright color and rich and luxurious characteristics of its flowers, with bright flower colors, changeable flower types, and extremely rich varieties, so it is an important garden flower in summer and autumn, especially suitable for flower landscape or garden bush planting.
Dwarf varieties are particularly suitable for potted ornamental plants or in flower beds, while tall varieties are suitable for cut flowers.
1. Types of dahlias and their introduction.
There are 30,000 impressive varieties of dahlias in the world, and they show their unique charm due to their wide variety of plant heights, flower shapes, flower shapes, and flower colors.
According to the height classification of the plant, dahlias can be divided into tall, medium, dwarf, and very dwarf types.
The tall dahlia plant is stout, about 2 meters high, with few branches, and the medium-sized dahlia plant is 10～1.5 meters, the most abundant flower types and varieties.
Dwarf dahlias are 06～0.9 meters, mainly chrysanthemum-type and semi-double-petaled varieties, with relatively few flowers, while very dwarf dahlias are 20 to 40 cm tall, mostly single-petaled, and the flowers are rich. Dahlias are often propagated by sowing seeds.
In addition, according to the different flower colors, dahlias can be divided into white, pink, yellow, orange, red, fuchsia, violet, purple and multicolor.
Among the varieties of dahlias, there is also a category called small lilys, which are relatively short in size, colorful in flower color, and the full flowering period coincides with the National Day, which is very suitable for home potted ornamentation.
At present, there are more than 7,000 varieties of dahlias cultivated in the world, and some of the common cultivars include Shouguang, Chaoying, Beauty, Huazi, Ruibao, Fushou, Jewelry, Hongfei, Xinquan, Hongpin, etc.
These varieties have their own characteristics, enriching the variety of dahlias and bringing more choices for people's horticultural appreciation.
In terms of ecological habits, dahlias are considered to be one of the most widely cultivated ornamental plants in the world.
It is highly adaptable to the growing environment, with a suitable growing temperature of 10 to 25 degrees Celsius. In areas with cool summer climates and large temperature differences between day and night, dahlias grow and bloom better.
However, it is sensitive to stagnant water, but it is not drought tolerant, and prefers to grow in sandy loam soils with good drainage, good water retention and rich humus.
Dahlias prefer full sunshine, but too much sunlight can be detrimental to their flowering, so in general, give enough sunlight in the morning and proper shade in the afternoon.
Dahlias are typical short-day spring bulbous flowers that sprout and grow in spring, and when the climate is cool in late summer and early autumn and the days are getting shorter, the flower buds will differentiate and bloom.
After frost in autumn, the branches and leaves of dahlias stop growing and wither, entering a dormant state.
From budding to flowering, dahlias take at least 120 days or more. It usually blooms from May to July in early summer and from September to October in autumn, with autumn blooming more luxuriantly.
The flowering period of a single flower lasts about 10 to 20 days, and the exact length of the flowering period depends on the variety and the temperature at that time. After pollination of the tubular flowers, the seeds will mature after about a month.
2. The propagation method of dahlias.
Dahlias are propagated mainly by ramifications (roots) and cuttings, both of which are the main methods of propagation. In addition, dahlias can also be propagated by sowing seeds to increase the population.
1. Spread (root) propagation.
March to April is the best time before the dahlias germinate, when we take out the stored roots and divide them before planting.
Since the bud point of dahlia is usually attached to the root neck, a part of the root neck with bud points must be left when the tuber root division is performed.
If there is no root neck with bud points on the tuber, then no new plants can be formed. If the bud spots on the root neck are not obvious enough, we may need to germinate in advance.
In general, we place the roots in a hotbed, then cover the roots with soil, water them and wait for the bud spots to appear, and then divide and plant them.
The propagation method of ramets (roots) is relatively simple and has a high survival rate, but the reproduction coefficient is relatively low, that is, the number of new plants that can be propagated by each mother plant is limited.
2. Propagation by cuttings.
Cuttings are generally used for mass propagation of dahlias, while propagation by cuttings can be carried out from early spring to summer and autumn.
When selecting land for land preparation, we should first choose a flat terrain, loose and fertile soil, and well-drained fields, and the most ideal soil quality is sandy soil.
When preparing the plot, it is possible to combine the application of superphosphate 033kg hm of fertilizer and plough the land to a depth of about 15 cm, then level it to form a furrow about 2 m wide.
In the period from June to August, when the new side branches of dahlias grow to 15-20 cm, cuttings can be cut in combination with the method of removing side buds.
Keep at least 3 buds on each cutting, and insert the thick end into the soil for about 10 cm.
It is best to use rooting powder to dip the insert end before cuttings and then water thoroughly. Immediately erect a shade net to shade the shade, and if there is no rainfall, water it twice a day.
After about 2 to 3 weeks, the cuttings will take root, and the flowering effect can be seen in the autumn of that year. After successful cuttings, it is necessary to weed frequently, and apply compound fertilizer once before and after flowering. In order to prolong the flowering period, it can be removed in time after the flowers are gone.
3. Seed propagation.
Seed propagation is more suitable for those dahlia varieties that are easy to set fruit, and dahlia seeds are generally harvested in autumn and then sown in the following spring.
When collecting seeds, it is necessary to choose seeds with full grains and good ripeness. Although the seedlings propagated by seeds have strong vitality, strong resistance and good adaptability, the flowering period is relatively late, and the excellent traits of the parents cannot be completely maintained, and sometimes even degraded.
Before sowing, choose a seedling tray that is commonly used for vegetable seedlings, which is usually 50 cm long and 30 cm wide.
Garden soil, humus and river sand are mixed into a matrix in a ratio of 2:2:1, and then disinfected, which can be disinfected by spraying 2% pentachloronitrobenzene or by high temperature disinfection.
If sowing is done on a hotbed, it is generally done in mid to late March. After sowing, place the seedling tray at an ambient temperature of 20 25 to keep the soil moist and avoid soil drying and compaction.
Seeds usually start to germinate about 7 days after sowing. When the height of the seedlings reaches 4 5 cm, the seedlings can be separated. After the seedlings are watered thoroughly, then they are placed in the shade for 2 to 3 days, and then moved to natural light.
When sowing in the open field, it is usually chosen to take place in mid to late April. The seeds are first sprinkled on the seedbed and then covered with moistened fine soil with a thickness of about 05 1 cm.
In order to increase soil temperature, maintain soil moisture and reduce water loss, it is best to cover a layer with bamboo poles to support agricultural film after sowing.
After the seedlings emerge neatly, the agricultural film can be removed, and then placed in a cool place for 2 3 days, and then moved to natural light for growth.
3. Maintenance and management of dahlias.
1. Pruning. The pruning of the dahlia is essential for its flowering, and in order to promote the early flowering of the dahlia, the single bud is usually retained during pruning; After the dahlia blooms, it generally leaves one or two nodes and then it is shortened.
For varieties with fewer branches, topping at the juvenile age of the plant can help promote the growth of multiple lateral branches. In addition, the plants are shortened in the summer, usually in July and August, and can also be used to promote flowering in the autumn from September to October.
2. Build flower nets and keep warm.
Once the plant height of the dahlia reaches 20-25 cm, it is time to consider placing a stent net. This mesh is usually fixed at a height of about 45 cm above the ground.
This helps to support the plant, prevent it from lodging, and provide a good support and environment for the flowers to grow.
In early spring, you can choose to plant the dahlias in a greenhouse in order to enjoy the blooming of dahlias in advance.
Growing dahlias in greenhouses allows for better control of environmental conditions, ensuring that the temperature does not exceed 25 degrees Celsius during the day and 10 degrees Celsius at night.
3. Flowering period control.
The shortening of daylight hours and the decrease of ambient temperature will affect the formation of flower buds in dahlias, which in turn will affect their flowering. Especially in winter and spring, dahlia bud formation may be hindered if there is not enough sunlight during the day and the temperature is too low at night.
In order to promote the blooming of dahlias in abundance, in winter and spring, the following measures can be taken: control the light hours during the day to about 14 hours, which helps to simulate the appropriate growing environment.
At the same time, keep the night temperature above 10 degrees Celsius, which can provide sufficient temperature conditions to promote flower bud formation and growth.
4. Fertilization management.
Dahlias love fertilizers and are essential for fertilizer application during growth. If there is a lack of sufficient fertilizer, it will affect the flowering of dahlias, causing the flowers to become smaller and darker, thus reducing their ornamentality.
In general, dahlias need to be fertilised 4 to 5 times in a growing cycle, and the principle of "more times and less application" should be followed.
It is best to choose farmhouse manure as a fertilizer, as it is rich in organic matter and can provide comprehensive nutrients to plants.
Special attention should be paid to the fact that in the summer, when the temperature exceeds 30 degrees Celsius, fertilization should be suspended to prevent excessive fertilizer from causing heat damage or other problems to plants.
5. Moisture management.
During the growth stage of dahlias, it is necessary to pay attention to controlling the amount of watering to avoid overgrowth of the plant, resulting in thick stems and oversized flowers.
Therefore, watering should be controlled in moderation and not too much.
Especially in the summer when the temperature is high, consider increasing the frequency of foliar spraying 2 times a day, which helps to reduce the temperature of the plant, maintain the humidity of its growing environment, and at the same time contribute to the healthy growth of the plant.
6. Temperature control.
Dahlias prefer cooler climates, and their optimum growing temperature is between 15 and 25 degrees Celsius. During the high temperature season, some cooling measures need to be taken to help dahlias maintain a suitable growth environment.
Among them, the methods of cooling include spraying water on the ground and using shade.
Water can be sprayed on the ground to reduce the surrounding temperature by evaporating heat dissipation, thus providing a relatively cool environment for dahlias to grow.
Perhaps the use of shade is also an effective way to cool down, reducing direct sunlight exposure and reducing the degree of heat exposure to the plants, which is conducive to keeping the growing temperature low.
Epilogue. In the process of cultivating dahlias, pay attention to factors such as temperature, light, moisture and fertilizers to harvest a beautiful picture.
The right growing environment can promote the growth and flowering period of dahlias. Timely fertilization, moderate watering, cooling and sun protection are all key to ensuring the healthy growth and blooming of dahlias.
Through careful care, the beauty brought by these elegant and gorgeous flowers can be appreciated to the eye.
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